Utility Will-Serve Letters: What They Mean and What They Don’t

A will-serve letter (also called a willingness-to-serve or intent-to-serve letter) is a short letter from an electric, water, sewer or gas utility responding to a request about a specific property. It typically confirms that the parcel lies in the utility’s service territory, describes the nearest facilities, and states that the utility can or will provide service subject to its rules and the customer’s compliance with them. The City of Mesa, Arizona, for example, describes its letters as based on existing system conditions and the project’s projected demand.¹

Landowners, lenders and local governments ask for these letters because they are the cheapest written evidence that utilities exist and that the provider is willing to talk. Developers use them early in site selection, often before they have site control or a firm load profile. That timing is exactly why the letters say so little: the utility is answering a general question about a parcel, not approving a specific load on a specific date.

Utilities that publish will-serve policies are unusually direct about the limits. Mesa states that a will-serve letter “does not serve as a reservation of capacity,” and warns that capacity sufficient on the date of the letter may become inadequate if the project is not connected in time.¹ Gastonia, North Carolina, distinguishes general communication about nearby sewer lines, which does not reserve capacity, from the specific instruments that do: a sewer permit, approved site plans or a formal willingness-to-serve letter under its allocation policy.²

For a data center, the gap between the two columns is the whole project. A 300 MW campus depends on transmission capacity, a new or expanded substation and often network upgrades that the utility has not yet studied when it writes a will-serve letter. Until a utility load study is done, a letter can honestly say the utility will serve the property while saying nothing useful about whether 300 MW is available in 2028.

Recent large-load tariffs make the sequence explicit. Under the AEP Ohio data center tariff, a prospective customer requests a load study and pays a study fee, then must sign a letter of agreement and a service agreement within set windows; missing the deadlines means the request is treated as withdrawn.³ The letter of agreement requires the customer to reimburse AEP Ohio for 100% of construction costs if it cancels the project or delays it by more than 12 months.³

The service agreement is where capacity becomes a two-way commitment. The Public Utilities Commission of Ohio approved the AEP Ohio tariff in a July 9, 2025 order.⁹ It requires new data centers above 25 MW to pay for at least 85% of their subscribed demand for up to 12 years, regardless of actual use.⁴ Our guide to large-load tariffs and electric service agreements covers those terms; the point here is that nothing comparable sits behind a will-serve letter.

Utilities have reason to keep early letters vague. Trade reporting describes developers flooding utilities with speculative “phantom” requests, the same project being shopped to several providers, and no standardized transparency for load requests, which makes real demand hard to separate from duplicates.¹⁰ Experts quoted by Propmodo estimate five to ten times more requests than data centers that will actually be built.¹¹ A utility that issued firm-sounding letters to every requester would be overcommitting the same substation many times over.

Legislatures are responding by moving the commitment earlier and attaching costs to it. Texas Senate Bill 6, enacted in 2025, directs the Public Utility Commission of Texas to set interconnection standards for loads of 75 MW or more, including proof of site control, a screening study fee of at least $100,000, and disclosure of substantially similar requests elsewhere in Texas.⁸ The commission’s March 2026 draft rule proposed a non-refundable interconnection fee of $50,000 per MW; when it adopted the final rule on September 18, 2026, it dropped that fee and set a flat $100,000 study fee regardless of load size.¹² Check the rule’s current text before relying on any figure; see our guide to Texas Senate Bill 6.

Local governments now use will-serve letters as a filter at the zoning stage. In 2026, Weld County, Colorado, approved Code Ordinance 2026-01 on a 4–1 vote, adding data centers to its code and requiring a will-serve letter from the electricity provider, along with proof of water, in site plan and special use applications.⁵ A proposed ordinance in York County, Virginia, would require a letter from the electric utility showing sufficient proximity to, and availability of, a substation and transmission lines to serve the proposed data center.¹³

Policy advocates want more. The AI Now Institute recommends that approval be conditioned on a contractual agreement with the utility affirming existing capacity, and that will-serve letters disclose whether the utility expects to need new generation or infrastructure to serve the project.¹⁴ Where a county adopts language like that, the letter becomes a more demanding document, and utilities may take longer to issue it or decline until a study is done. Applicants should ask the planning department early what the letter must say, and our guide to annexation and utility service areas covers cases where the service provider itself is in question.

Read the letter for what it actually states, then list what it leaves out. The table below shows the usual clauses and the questions each one should prompt.

Expiration terms vary by utility but are common, especially for water and sewer. The Indian Hills General Improvement District in Nevada lets its letters expire one year after issuance, with board extensions if the owner is making substantial progress.⁶ The Los Osos Community Services District in California sets two years, extendable for good cause.⁷ Gastonia ties sewer allocation to approved site plans that expire if construction has not begun within a year.² For data center water questions, see our guide to municipal water and sewer capacity.

1. 01Ask the utility what its letter will and will not state before you request it, and allow processing time; Mesa, for example, advises three to four weeks.¹
2. 02Give a realistic load and ramp schedule. A letter based on a 5 MW request says nothing about 200 MW.
3. 03Request separate letters for electric, water, sewer and gas; each provider answers only for its own system.
4. 04Treat the letter as an entry ticket to a load study, and budget for study fees and early cost exposure.³⁸
5. 05Track expiration dates and renew before a zoning hearing or a buyer’s diligence deadline.⁶⁷
6. 06In land contracts, define the utility response that satisfies a power contingency. A will-serve letter alone is a weak trigger; see our guide to letters of intent for data center land.

A will-serve letter is useful when you read it for what it is: confirmation of the provider and an open door. If you want help reading a utility response against a site’s actual power, water and timing needs, you can get a site reviewed.